Surface planarization is an important requirement for device reliability and depth-of-focus (DOF) requirements of optical microlithography used for semiconductor device fabrication. DOF issues arise when attempting to focus a mask pattern on a semiconductor wafer surface area that has an uneven topography. The portion of the surface farther away from or closer to the imaging lens can be out of focus with respect to the portion of the surface closer to or further away from the imaging lens. It is desirable, then, to have device surfaces be as planar as possible. As semiconductor fabrication technologies are scaled to sub-0.5 .mu.m dimensions, however, improved planarization techniques are necessary in order to achieve satisfactory global surface planarization for the microlithography tools with more stringent DOF requirements.
Global planarization involves complete planarization over the entire chip area. To date, chemical mechanical polishing (CMP) and plasma deposited polymer films plus etch back are the only practical global planarization methods proposed for semiconductor device fabrication. Moreover, CMP is the main and only proven global planarization technique that can be used for sub-0.5 .mu.m semiconductor technologies. But successful implementations of CMP for semiconductor device fabrication demands effective post-CMP cleaning process in order to remove CMP-induced surface contaminants and damage. Therefore, much work remains to be done in order to make CMP a fully useable global planarization process.
To date, there is no known practical in-situ method for globally planar material layer deposition. As a result, there is no method or system that permits simple in-situ global planarization of material layers and that avoids the complications and adverse effects on device yield such as those of CMP.
Consequently, there is a need for a globally planar material layer deposition method and system for advanced semiconductor device fabrication technologies.
There is a need for a globally planar material layer deposition method and system that meet the depth-of-focus requirements of advanced microlithography tools.
There is a further need for a globally planarized material layer deposition method and system that may be performed in-situ and that is simple and avoids the damage and contamination problems associated with other known methods such as chemical-mechanical polishing methods.